替代HTTP Mock策略

使用MockBackend的一个替代方法是创建我们自己的轻模拟。 这里我们创建一个对象，然后告诉TypeScript使用类型断言将其视为Http 。 然后我们为它的get方法创建一个监测器，并返回一个类似于真正的Http服务的observable 。

此方法仍然允许我们检查服务是否已请求正确的URL，并返回预期的数据。

wikisearch.spec.ts

  1. import {
  2.   fakeAsync,
  3.   inject,
  4.   TestBed
  5. } from '@angular/core/testing';
  6. import {
  7.   HttpModule,
  8.   Http,
  9.   ResponseOptions,
  10.   Response
  11. } from '@angular/http';
  12. import { Observable } from 'rxjs/Observable';
  13. import 'rxjs/add/observable/of';
  14. import {SearchWiki} from './wikisearch.service';
  16. const mockResponse = {
  17.   "batchcomplete": "",
  18.   "continue": {
  19.     "sroffset": 10,
  20.     "continue": "-||"
  21.   },
  22.   "query": {
  23.     "searchinfo": {
  24.       "totalhits": 36853
  25.     },
  26.     "search": [{
  27.       "ns": 0,
  28.       "title": "Stuff",
  29.       "snippet": "<span></span>",
  30.       "size": 1906,
  31.       "wordcount": 204,
  32.       "timestamp": "2016-06-10T17:25:36Z"
  33.     }]
  34.   }
  35. };
  37. describe('Wikipedia search service', () => {
  38.   let mockHttp: Http;
  40.   beforeEach(() => {
  41.     mockHttp = { get: null } as Http;
  43.     spyOn(mockHttp, 'get').and.returnValue(Observable.of({
  44.       json: () => mockResponse
  45.     }));
  47.     TestBed.configureTestingModule({
  48.       imports: [HttpModule],
  49.       providers: [
  50.         {
  51.           provide: Http,
  52.           useValue: mockHttp
  53.         },
  54.         SearchWiki
  55.       ]
  56.     });
  57.   });
  59.   it('should get search results', fakeAsync(
  60.     inject([SearchWiki], searchWiki => {
  61.       const expectedUrl = 'https://en.wikipedia.org/w/api.php?' +
  62.         'action=query&list=search&srsearch=Angular';
  64.       searchWiki.search('Angular')
  65.         .subscribe(res => {
  66.           expect(mockHttp.get).toHaveBeenCalledWith(expectedUrl);
  67.           expect(res).toEqual(mockResponse);
  68.         });
  69.     })
  70.   ));
  72. });

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